The present invention is generally related to a method for producing semi-leather fibrous tissue sheets, and more particularly to provision of the choice of raw material composed of short-cut animals' leather pieces so as to produce semi-leather sheet products such as what is called "backskin" sheet, by planting these pieces on a woven or unwoven basic clothing sheet in uniformly and inseparably attached relation to the outside surface area of the sheet. Thus are finished sheet products reproducing animals' leather sheets most similar to the original leather of animals' skin.
With a view to artificially reproducing leather sheets similar to animals' leather there have been practically applied such well known method in the field of skilled arts for example as of cutting animals' leather into short length and resoluting the cut amount thereof.
However, as in shown in FIG. 1(A) of the accompanying drawings, most of the artificially finished leather fabric tissues 1 produced by the conventional method are, as the whole, doomed to be curled and frizzled unexceptionally to excess because each of tissues 1 or fiber elements cannot but be accompanied with a number of bristles and sprays or twigs 1a. Thus in case of planting these tissues 1 on a basic clothing sheet 2 by means of a binder 3 with respect to FIG. 1(B), there is no expectation to plant uniformly on the basic clothing sheet 2 almost equal number of tissues, differently from any natural or animals' fiber elements 1. Also it is infeasible to plant a pre-determined number of the conventional fibers on the basic clothing sheet 2 per fixed surface area, thus resulting in the fibers having some portions densely planted while other portions are thinly planted. Moreover, due to the structurally curled and frizzled conditions of the existing fibrous tissues, an extremity of each fiber element cannot be fully pierced into adhesive layer of the basic clothing sheet 2; wherein some fiber elements are left, at the midway thereof, stuck to the basic clothing sheet 2, thus giving rise to a difficulty that desired planting effeciency cannot be secured.
As has been mentioned in the foregoing description, even if animals' leather fibrous tissues are to be carefully planted or pierced onto the basic clothing sheet 2 in accordance with the conventional manufacturing methods, the leather fibrous tissues thus produced are still essentially short of piercing power. As a result the sensitive tone of slipperiness peculiar to animals' leather fibrous tissues themselves cannot be reproduced on the basic clothing sheet 2 when baffing operations are applied thereto since, during the course of this operation, a number of fibrous tissues entangled or twisted with each other are forcibly to come off the basic clothing sheet 2 by baffing power which is repeatedly and unavoidably added to the entangled or twisted force of the planted fiber elements per se.
Furthermore, referring to the conventional semi-leather fibrous tissue sheets, it is technically impossible to plant these tissues or fiber element 1 on the basic clothing sheet 2 through the whole surface area thereof, consequently bringing about disadvantages that the products thus finished are inferior to animals' leather sheet products with respect to strength and durability in practical use. In addition thereto, when the planted tissues 1 are dyed either from men's sense of beautiful color or in obedience to any color of animals' leather per se, no effect can be reproduced much less of animals' leather colours because the planted fiber elements 1 are inevitably dyed thick on the portions thereof aslant to the basic clothing sheet 2 only, so that, compared with other thin planted portions, the former portions are subjected to different light refrection from the latter portions whereas animals' leathers are reflected uniformly to equal reflection of colour through the whole surface thereof from any angles.
The main reason, among many others, why conventional semi-leather fibrous tissues 1 are fatally curled and frizzled through the course of treating operations is considered to be attributable to neglegence of the most important facts that animals' leathers in the form of a raw material must be cut into short length and a suitable quantity of water be added to said pieces, thereafter being cut or smashed by means of a sharp cutting blade.
In other word, animals' leathers are widely accepted to be good enough to cut them into a short length only without paying attention as to how important it is to add a suitable quantity of water to the amount of cut pieces and select a smashing means for cutting said pieces to further cut the pieces into shorter length. Namely, according to the existing cutting method, the raw material is forcibly cut into short length by tearing off the material by use of cutting instruments having on obtuse blade edge, regardless of the percentage of water contained an the raw material. For a fuller understanding, a maximum elemental unit composing animals' leather fibrous tissues 1 is a bundle which comprises a group of fibers gathering together with each other, in which each of the fibers is composed of plurality of fiber elements having diameters between 4 and 8 microns, respectively, further each of said fiber elements comprising several hundred pieces of fibrils, as are generally well known in the field of skilled art.
In spite of the above-mentioned properties peculiar to animals' leather fibrous tissues 1, the realities are that use is made of such a dull implement as the obtuse knife as has already been referred to in the foregoing description to comminute or smash thereby the animals' leathers into short length of pieces without mixing the former with a suitable quantity of water just when the smashing operation is being carried out. Thus to say nothing of said bundles and said fibers, both the fiber elements and the fibrils that compose the former two and are of by far diametrally smaller elemental components thereof are also directly subjected to the effect of this smashing operation until at last the latter two are broken up; consequently, this quantity of dismantled fibers and fibrils are branched off in free directions to give rise to bristling and branching-off phenomena.